If you’re migrating from one iMac to another (shinier) one after the holidays, or helping someone set up their new MacBook Pro to replace their old MacBook Air, you might be tempted to use iCloud Drive to move some important files you need to access in a hurry. Unfortunately, if you’re moving files from a Mac running Sierra to one running High Sierra, your documents, images, and other files might lose some metadata in the process.

Writer Howard Oakley wrote about a peculiar bug that occurs when transferring files using Apple’s iCloud Drive, its cloud storage service that lets you sync files like images, documents, and whatever else you’ve got between macOS and iOS devices. Should you attempt to copy a file containing a particular list of extended attributes that make up a file’s metadata from Sierra to iCloud to High Sierra, those attributes are no longer included in the new file on the Mac running High Sierra.

Oakley’s examples included a text document with additional metadata in the form of a custom icon, and PDF annotated with various notes. While a lost icon on a text file might not mean much, losing notes and edits made on a PDF might spell disaster if that iCloud Drive file becomes your only copy when you’re moving from an older Mac to a new one. The problem is pretty particular but should still be one to note if you see a new Mac in your future. High Sierra has had a number of security issues as of late though, so I don’t blame you if you’d rather wait a little longer before you update your Mac.